Chev C70 with stuck 5 & 4

hey guys... I purchased a C70 at a auction a few months back that is in good shape. Has a 427 that was rebuilt... new driveshafts and rear ends...Now the truck shifts great and when I used it in the fall the aux tranny shifted alright.. but during the last few loads it was stuck and now I cant get it out of drive. Seems like its jammed in there. I am not to familiar with the 5&4. Can I take the plate thats on top of the transmission to see whats going on inside?.

Yes. It's probably a Spicer 7041.

Check the linkages running into the trans too. I had the "U" brake on mine so it wouldn't shift out of 3rd.

While I think of it, anyone know if running 80w90 ok? 5052c main trans, 7041 aux

It's been a lifetime since I've been around a truck with a "pair of sticks" (my favorite transmission configuration). If I remember correctly, the older they got, the more likely the tranny linkages would lock up if they weren't shifted just right. When they locked up, we simply got a pry bar or something and wiggled the linkages back and forth a bit on top of the tranny and that got things working again. Never needed to take anything apart. Hope this helps and good luck.

If its like the aux trans in my truck (80s c70) there are two rods going from the shifter to the trans. One rod for 1st and 2nd gear, the other for 3rd and 4th.
When I had an issue with mine the end of the rod broke. I ended up dabbing a new piece.

The top cover comes off and you can get into the trans.

What happens is the end of the stick gets out of the slot in the plunger (shift rail)before it is in the center(neutral) position. The stick ends up in the other plunger slot but it won't move because the first shift rail is still in gear and the interlock mechanism in the transmission lid keeps it from moving into two gears at once. There's nothing wrong inside the trans, the shifter is either worn out out missadjusted. When it sticks, just put both plungers in neutral and it will be freed up.